Stroboscopic device for checking and adjusting meters



" July 5, 1938. G. E. MAILLAT 2,123,115

V STROBOSCOPIC DEVICE FOR CfiECKING AND ADJUSTING METERS Filed July 28,1 956 4 Sheets-Sheet 1 July 5, 1938; G. E. MAILLAT 2,123,115

'STRQBOSCOPIC DEVICE FOR CHECKING AND ADJUSTING METERS Filed July 28,1936 4 Sheets-Sheet 2 I July 5, 1938. 6,5, MAILLAT 2,123,115

STROBOSCOPIC DEVICE FOR CHECKING AND ADJUSTING METERS Filed July 28,1936 4 Sheets-Sheet s July 5, 1938. 2,123,115

'STROBOSCOPIC DEVICE FOR CHECKING AND ADJUSTING METERS G. E. MA lLL AT 4Sheet-Sheet 4 Filed July 28, 1936 I 6 MF/Y/Vi ivvelv-f w Patented July5, 1938 s'rnonoscorro ni-zvron'roa CHECKING ANDADJUSTING METERS GustaveErnest Maillat, Voisins-le-Bretonneux,

by Trappes, France,

assignor to Union dElec- 1 tricite, Paris, France, a French companyApplication July 28, 1936, Serial No. 93,065 In France August 10, 1935'7 Claims.

The present invention relates to a stroboscopic device for checking andadjusting meters. It is known that the construction of such a devicegives rise to a considerable difliculty due to the very slow speed ofrotation of the meter discs particularly on light loads, which preventsobtaining sufliciently'distinct and quick variations of luminousintensity to makethe stroboscopic phenomenon visible.

In order to overcome this drawback, recourse has been had in the knownstroboscopic apparatus, to an intermediary device transforming theslight variations of luminous intensity into variations of electriccurrent and supplying in its turn a luminous source which gives rise tosuit able variations of illumination. Thus these apparatus usuallycomprise a. luminous source the beam of which is projected throughserrations provided in the disc of the standard meter onto aphotoelectric cell which supplies a neon tube or the like which issuitably polarized so as only to light in the region of maximumillumination of the cell and serving for periodically illuminating thedisc of the meter to be checked which on the other hand, attempts havebeen made nous beam which is periodically interrupted by the serrationsof the disc of the standard meter, is projected directly onto the discof the meter to be checked, but such devices only enable an particularrenders checking impossible in broad daylight without using a specialdark room.

The device according to the present invention is intended to overcomethis drawback and it is is projected from below onto the under face,which is provided with a graduation, of the disc of the meter to bechecked, and that behind the luminous source and the serrated disc ofthe standard meter is arranged a fixed screen pro vided withcorresponding serrations.

' The combination of these two means, viz. the

projection of the periodically interrupted luminous beam, on the underface of the disc of the meter to be checked, and the interposition of toconstruct simpler devices in which the lumiinsuiiicient illumination tobe obtained, which in characterized by the fact that the luminous beam 7a fixed serrated screen, enables the operation to be readily carried outin broad, daylight with a luminous beam of relatively small intensitysince, on the one hand, the under face of the disc of the meter isalways in almost complete darkness and, onthe other hand, the periodicvariations of the intensity of said beam, duev to the serrations of thedisc of the standard 'meter, are rendered very distinct owing to theserrations of the fixed screen.

By way of example two embodiments of the. device according] to theinvention have been described hereinafter and illustrated in theaccompanying drawings.

Fig. 1 thereof is a diagrammatic perspective view.

Figs. 2, 3 and 4 concern the construction of the serrations andgraduations of the discs of the meters and of the fixed screen.

Figs. 5 and 6 show diagrams of electric connections.

Fig. 7 shows a perspective view of a first embodiment of the device andthe method of fixing same on the meter to be checked whereas Fig. 7a isa sectional view taken on the line la-la of Fig. 7. i

Fig. 8 shows a diagram of the electric connections of an improveddevice.

' Fig. 9 shows the detailed, method of construction of said device, and1 Fig. 10 is a sectional view taken on line l0l0 of Fig. 9.

The apparatus of which the diagram is shown in Fig. 1 comprises astandard meter 1 the disc 2 of which is provided with serrations3.serving to periodically interrupt a luminous beam issuing from the lamp4 and projected by the lens 5 and the prism 6 through the intermediaryof the serrations 1 of a .fixed dividing screen 8. Afterv passingthrough the serrations 3...of 'the disc 2, the luminous beam which isperiodically interrupted by said serrations, is sent by a prism 9provided on two of its faces with cylindrical lenses 9', 9" the axes ofwhich are perpendicular to each other and which projects a beam ofrectangular shape onto the under face of the disc Ill of the meter 14 tobe checked which face is provided with a graduation l l the stroboscopicphenomenon being observed by means .of a magnifying glassll placedagainst a prism l3. or by means of a concavemirror.

In order to increase the darkness surrounding the under face of the discI0, the'meter I to be checked is provided with an opaque screen 15'arrangedin front of said disc and provided with a window l3 throughwhich the lumincusbeam, which is projected onto the graduation I I bythe prism 8, is projected onto the prism l2l3. The window It isadvantageously provided on'its upper edge with a pointer i'lfacilitating the reading. In the case of meters provided with a glasscasing, the prescribed address plate can play the part of the screen I5,it will suflice'in this case to make the inspection window i6 in saidplate. In order to make the stroboscopic phenomenon visible for lightloads of the meter, corresponding to very low speeds of rotation of thedisc, it is necessary to construct very close serrations on the disc 2of the standard meter and on the fixed screen 3, for example three teethper degree of arc. Since the construction of such serrations on a discof small diameter is exceedingly diflicult,

. it is carried outin the following manner: a circular ring is providedwith radial lines l9 having the required angular spacing between them,the thickness of the lines being equal to their spacing, is drawn on avery much enlarged scale (Fig. 2) and photographs are taken thereof ofthe desired size: the graduated rings cut out of the negatives printedon transparent films are crimped on the periphery of the discs of thestandard meters of which they replace the serrations. The graduation ofthe' disc of the meters to be checked is printed in black on said discsof which the surface is previously frosted, the portion ll of the lines(Fig. 3) located near the edge of the disc being slightly offsetrelatively'tc the main-graduation 'l I.

When the disc of the standard meter carries, as hereinbefore indicated,a graduated ring consisting of a film, the fixed screen 8 should have acertain thickness in order to guide the luminous .rays over a length ofabout one millimeter. Consequently in order to construct serrations ofsuch a thickness but as close together as those of the disc of thestandard meters, thin sheet metal I blades 23 are assembled together asshown in Fig. 4, said blades being separated from each other by shorterblades 2i, so .as to form an extremely fine comb 'of circular orrectilinear contour. On the contrary, when the disc of the standardmeter carries serrations cut on its periphery, the serrations of, thefixed screen 3 can consist of a film in the above referred to manner.

As shown in Fig. 5, the terminals 22, 22' of the current winding 23 ofthe meter to be checked are connected to the terminals 24, 24' which areconnected to a current transformer 25, a switch 23 being disposedbetween the terminals 22', 24

and another switch 21 between 24 and 24'. The

current winding 23 of the standard meter is connected between theterminals 22' and 24' in series with a rheostat-transformerdiagrammatically illustrated at 29 and adapted to be short circuited bya switch 33. When checking at the normal load, the switches 23 and 21are opened, whereas the switch 30 is closed, so that the windings 23-and 25 of the two meters are connected in series. For eiiecting anadjustment at all loads, it is necessary to short circuit the currenttransformer by closing the switch 21 and to bring therheostat-transformer 23 into service by opening the switch 33.

Fig. 8 shows the diagram of the connections of the voltage windings ofthe two meters. The terminals 3|, 3| are connected to avoltagetransformer 32 and supply a potentiometer consisting of a fixedresistance 33 and a variable re- 's'stance 34. A double throw switch 35enables either-of the two voltage. windings and 31 of .ue of theresistance 34 is reduced so, as to decrease the voltage supplying saidmeter, until the disc ii of the meter to be checked appears to bestationary. Since the speed of the disc of a meter is proportional tothe voltage, the potentiometer 34 can be directly graduated in errorpercent, thereby making thestandardizing extremely easy and rapid.According to a preferred embodiment of the apparatus, the standardmeter, the luminous source 4 with its optical system 5, 6, I, 8, 9, l2,I3, the fixed screen 3, the potentiometer 33, 34 and the double throwswitch 35 are lodged in one and the same casing 33 (Fig. '7) which isfixed by means of pins 39 on the checking plate 40 of the meter l4 to bechecked which is provided for this purpose with sockets 4| suitablyconnected to the windings of the meter for effecting all the connectionsshown in Figs. 5 and 6 when the casing 38 is mounted, including theopening of the switch 26 which is also lodged in said casing. In Fig. 7,the rheostat-transformer 29 controlling the variations of the load ofthe meters during the standardizing operation, has been shownseparately; 01' course it can also be lodged in the casing 33, as willbe indicated in another embodiment hereinafter described. f

Fig. 8 shows in detail in the case of a single phase meter, a morecomplete diagram of connections with the connections of the standardmeter and of the various adjusting members with the pins by means ofwhich the apparatus contained in the casing 38 is fixed on-the plate 40of the meter to be checked. Said plate 40 has for this purpose eightsockets 42, 43, 44, and 42, 43, 44', 45' the current and voltagewindings 4i and 41 of the meter to be checked being respectivelyconnected to the sockets 4243 and 44-45, whereas the sockets 42', 43'and 44, 45' are connected to the supply mains, or, in the case of a hightension meter to the current and voltage transformers 48 and 43, thesockets 42-42 and 44-44' being respectively connected to each other.Furthermore, the terminals 43-43" and 45-45 are respectively connectedby contacts pins of the casing-38 by the same numerals asthecorresponding sockets of the plate 43, the connections of the standardmeter and of the various adjusting and switching members are as follows:the primary 50 of a transformer 5i is connected to the pins 44'---45' aportion 52 ofsaid primary being shunted by a rheostat 53 graduated inerror per cent and which can'be connected by a double throw switch 54either to the pin 45 for adjusting the supply voltage of the meter to bechecked, or to the pin 45 for adjusting the supply voltage of thevoltage winding 55 of the standard meter. The current wind ing 56 of thestandard meter is connected tothe pins 42 43; however, in series .withsaid winding is arranged a multi-way switch I! enabling either the'current windings 56 and 46 of the two .meters to be connected in seriesacross the ter- V ininals oi the current transformer 48, or to conformer3 For this purpose, the multi-way switch; 51 has nect'them, in order topermit checking at 'all loads, to the secondary 64 of the aforesaidtranss ix studs 58, 59, 6|], 6|, 62 and-63, the studs 58-450 beingrespectively connected to the pin 42' and to the current winding 56' ofthe standard meter,

, the stud'59 being connected to the pin 43, the

' nally, the studs 59 and GI are permanently constuds til-63 beingrespectively connected to the terminals of-the secondary winding 64- ofthe transformer 5| through the intermediary of an' adjusting rheostat 65and an adjustable choke 66, whereas the stud 6-2 is connected to anintermediate point 61 .of said secondary winding. Fi-

nected to eachotherby a conductor 68. fI'he multi-way 'switch is adaptedto. makethe following connections 1 1-. The studs 60-and 6| areconnectedto each,

otherso that the current windir'igs 56 and 46 of the two meters areconnected'in series across to each other, two by two, which" hasthe.efiect,-

2. The studs 5859 and BIL-62 are connected on the one hand, of shortcircuiting the current transformer 48and, onjthe other-hand, of con--necting the two windings 4B and 56 to the secondary winding 64 of thetransformer 5! through the intermediary of the rheostat 65, therebyenabling the checking operation to {be effected for all the loads inwatted current.

, 3. ,The studs 58 -59 and 6[|-63 are connectedtwo by two, so that asthe current transformer and switching members can be seen in- Fig, 9:the auxiliary transformer 51 is fixedibelow the casing 38, and likewisea casing l0 containing g the rheostat 85, the choke 66 and themulti-way' t8 always remainsshort circuited, the adjustable choke 66 isconnected in series, at the same time aslthe rheostat 65, with thewindings 46 and 56 of the two meters, thereby enabling the .'Iclaim.:

f *1. Stroboscopic device for checking and ads justing electric meters,comprising a standardmeter having a disc provided on its periphery withmeans for periodically interrupting light, a luminous source, opticalmeans for projecting a luminous beam issuing from .said source onto the'under' face of the disc-of the meter to be checked through theperiphery'of the disc of the standard meter, the under. face of the discof the meter to be checked having the same number of graduation lines asthe number of serrathe path of the luminous beam and interposed betweenthe luminous source, and the' serrated disc of the standard meter,

2. Stroboscopic device-for checking and admeter having a disc fserr'atedat its periphe'ry,-a luminous source, optical means for projecting aluminous beam issuing from said source onto the under face of th'ediscof the meter to be checked,' through the serrations of the disc of 25the standard meter, the under face of the disc of the meter to bechecked having the same number of,graduati0n lines as the number of'serrationsof the disc of the standard meter, a

fixed screen provided with serrations arranged in the path oi theluminous-beam and interposed between the' luminous source and the serrated disc of the standard meter, and an opaque tions of the disc ofthestandardmeter, and a a fixed screen provided with serrations arrangedin justing electric meters comprising a standard screen provided with aninspection window,- arranged in front of checked.

3. Stroboscopic device for checking and adjusting electric meters,comprising a plate fixed the disc'of the meter to be,

below theri'neter to be checked and provided with contact sockets, atransportable casing containing a standard meter having a serrated-disc,a luminous source, an optical projection system for projecting a.luminous-beam issuing 'from a most usual checkings to be .eflfectedindephaseda; said source onto the under face; of the disc of current.

An auxiliary secondary winding 59 of the trans-' 'the'construction ofthe fixing plate 40 can .be

modifiedaccording to the type-of meteri,

The arrangementof these various adjusting switch 51. .Onthe front wallof said casing-I0 isinounted. a knob -II controlling themulti-wayswitch, and theknob l2 controlling the rheostat 65. On-a side wall ;ofthe casing 38 is mounted the double throw switch 54 and the knob 13 ofthe rheostat 53 adjusting the-supply voltage, said knob 13 beingprovidedw-itha pointer I! which "moves in frontoi agraduation 15 givingdirectly the error per cent,

On the casing 38 is arranged'a graduated dial' 16in front of whichrotates a pointer-.11 fast on the shaft ofthe standardv mete-L sa as toenable "thefrneters to be checked according .to the usual method.The'pointer'll is preferably provided.

with azero retracting device.' I

The casing 38 is provided with handles 18 and I hooking memberssuch asI9, sothat the whole.

by the connecting pins and sockets.

weight of the apparatus need not be supported the me er to becheckedthrough'theserrations of the disc of the standard-meter, afixedserrated screen arranged in the path of theluminous beam betweensaid source and the standard ranged on a side wall of 'sa-idvcasing andfitting. into the sockets of said platefiand means for effecting bymeans of said sockets andsaid pins the connections of thetwo meter'stothe supply mains. I

below the meter to .be checked and provided with contact sockets, atransportable casing contain-- ing a standard meter having a serrateddisc, a'

\, luminous source, an optical projection system -for projecting aluminous bam, issuing from .said source onto. the under face ofthediscof the meter-to be checked through the' serrations of the disc.of the standard meter, a fixed serof the" interruptions o f saidbeamadue to the serrated disc of the standard meter, such means uatedin' percent error} a double throw switch, means -for connecting saidpotentiometer by means of said double throw switch with the voltagewinding of either of the'two meters, a. rheo -l meter andmembers'forregulating the frequency f 1 of the interruptions of said beam due tothe serrated disc or the standard meter by adjusting -the supply currentand voltage, fixing pins are 5:. 4. Stroboscopic device for checkingandad V justing electric metersf-com'prising .aplate fixedratedscreen-arranged in the pathof the lumi- .nous beam betweensai'dsourceandthestandard meter, means .for regulating. the frequency comprising, astandardizing potentiometer grad-.-

stat-transformer and means for connecting said rheostat to the currentwindings of the two meters, fixing pins arranged on one of the sidewalls of said casing and fitting into the sockets of said plate, andmeans for effecting, by means oi said sockets and said pins, theconnections of the two meters, of the potentiometer and of the'rheostat-transformer to the supply mains.

5. Btroboscopic device for checking and adlusting electric meters,comprising a plate fixed below the meter to be checked and provided withcontact sockets, a transportable casing containing a standard meterhaving a serrated disc, a luminous source, an optical projection systemfor projecting a luminous beam issuing from said source onto the underrace of the disc oi the meter to be checked through the serrations ot'the disc oi. the standard meter, a fixed serrated screen arranged in thepath of the luminous beam between said source and the standard meter,means for regulating the frequency of the interruptions of said beam dueto the serrated disc oi. the standard meter, such means comthe socketsof said plate, and means for eflecting, by means of said sockets andsaid pins, the connections or the two meters and of the primary windingof said auxiliary transformer to the supply mains; I

6. Stroboscopic device for checking and adlusting electric meters,comprising a standard meter the disc of which is provided on itsperiphery with a ring out out from a transparent him, having a largenumber 01' radial lines in very close relation, a luminous source,optical means for projecting a luminous beam issuing from said sourceonto the under face of the disc of the meter to be checked,'through thegraduated transparent ring of the disc of the standard meter, the underrace of the disc of the meter to be checked having a number oigraduation lines equal to the number of graduations of the disc or thestandard meter, and a fixed screen provided with serrations arranged inthe path of the luminous beam, between the luminous source and theserrated disc of the standard meter.

7. Stroboscopie device for checking and adjusting electric meters,comprising a standard meter the disc of which is provided on itsperiphery with a ring cut out from a transparent flim, having a largenumber of radial lines in very close relation, a luminous source,optical means for projecting a luminous beam issuing from said sourceonto the under face of the disc of the meter to be checked, through thegraduated transparent ring oi. the disc of the standard meter, the underface 01' the disc of the meter to be checked having a number 01'graduation lines equal to the number of those on the graduatedtransparent ring of the disc of the standard meter, and a fixed screenarranged in the path of. the luminous beam between the luminous sourceand said transparent ring and consisting of an assembly of alternatelylong and short thin sheet metal blades forming a comb.

GUSTAVE ERNEST MAIL-LAT.

